Spatial light modulator comprising a liquid crystal device having reduced stray light

Patent metadata

Field	Value
Publication number	US-9810948-B2
Application number	US-201214425674-A
Country	US
Kind code	B2
Filing date	Sep 5, 2012
Priority date	Sep 5, 2012
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

The present invention relates to a controllable diffraction device for a light modulator device. The controllable diffraction device comprises at least two substrates, at least one electrode on each of said substrates facing each other, and liquid crystals forming at least one liquid crystal layer arranged between said electrodes on said substrates. The orientation of the liquid crystals is controllable by a voltage supplied to the electrodes. The liquid crystal layer is provided on at least one alignment layer arranged on at least one electrode on said substrates. The liquid crystals close to the alignment layer are pre-oriented by at least one pre-tilt angle relative to the alignment layer such that the resulting light diffraction in opposite spatial directions is approximately equal.

First claim

The invention claimed is:

1. Controllable diffraction device for a light modulator device in a display for presenting at least one of the following: stereoscopic image contents and stereoscopic multi-view image contents and holographic image contents, the controllable diffraction device comprising
at least two substrates,
at least one electrode on each of said substrates facing each other, and
liquid crystals forming at least one liquid crystal layer arranged between said electrodes on said substrates,
whereby the orientation of the liquid crystals is controllable by a voltage supplied to the electrodes and the liquid crystal layer is provided on at least one alignment layer arranged on at least one electrode on said substrates,
whereby the electrodes are arranged such that an electric field distribution is obtained, which realizes at least regionally a variable saw-tooth-shaped diffractive structure, when voltages are applied to the electrodes, and
whereby the liquid crystals close to the alignment layer are pre-oriented by at least one pre-tilt angle relative to the alignment layer such that the resulting light diffraction in opposite spatial directions caused by the saw-tooth shaped diffractive structure is approximately equal.

2. Controllable diffraction device according to claim 1 , whereby a polar pre-tilt angle θ is set to a value enabling a unidirectional rotation of the orientation of the liquid crystals in the liquid crystal layer.

3. Controllable diffraction device according to claim 2 , whereby the polar pre-tilt angle is in the range of 0°<θ<3° or 87°≦θ<90°.

4. Controllable diffraction device according to claim 1 , whereby the pre-orientation of the liquid crystals close to the alignment layer is further determined by at least one azimuthal pre-tilt angle φ.

5. Controllable diffraction device according to claim 4 , whereby different areas of the alignment layer provide different azimuthal pre-tilt angles φ.

6. Controllable diffraction device according to claim 5 , whereby the areas of the alignment layer are arranged repetitively in the form of stripes and the azimuthal pre-tilt angles φ are alternately φ 1 =0° and φ 2 =180°.

7. Controllable diffraction device according to claim 1 , comprising at least two alignment layers, whereby the alignment layers provide different azimuthal pre-tilt angles φ.

8. Controllable diffraction device according to claim 7 , whereby the azimuthal pre-tilt angles φ are φ 1 =0° for the first alignment layer and φ 2 =180° for the second alignment layer.

9. Controllable diffraction device according to claim 7 , whereby the polar pre-tilt angle is in the range of 10°≦θ<30° or 60°≦θ<80°.

10. Controllable diffraction device according to claim 4 , further comprising a switching device for switching the azimuthal pre-tilt angle φ by 180°.

11. Display comprising a light modulator device and at least one controllable diffraction device according to claim 1 , wherein the display is designed such that at least one of the following is presentable: stereoscopic image contents and stereoscopic multi-view image contents and holographic image contents.

12. Display according to claim 11 , further comprising a spatial light modulator with pixels comprising a pixel pitch, where areas of the alignment layer of the controllable diffraction device are arranged repetitively in the form of stripes and the azimuthal pre-tilt angles φ are alternately φ 1 =0° and φ 2 =180° and where the width of the stripes is set such that it is smaller than one half of the pixel pitch of the pixels of the spatial light modulator or where the width of the stripes is set such that it corresponds to one half of the pixel pitch of the pixels of the spatial light modulator.

13. Method for displaying at least one of two- and three-dimensional image content or image sequences, the method comprising the following steps:
varying at least one of the phase and amplitude of a substantially collimated light wave field by a light modulation device comprising a spatial light modulator and a controller;
diffracting the light wave field by at least one controllable diffraction device according to claim 1 having a variable diffraction structure.

Assignees

• Usukura Naru
• Katoh Hiromi
• Kanbayashi Yuichi
• Leister Norbert
• Haussler Ralf
• Sharp Kk
• Seereal Tech S A

Inventors

• Usukura Naru
• Katoh Hiromi
• Kanbayashi Yuichi
• Leister Norbert
• Haussler Ralf

Classifications

• G02F1/1393

  the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells (G02F1/1396, G02F1/141 take precedence) · CPC title

• G02F1/292

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical switching G02F1/31) · CPC title

• G02F2203/24

  beam steering · CPC title

• G03H1/2205

  using downstream optical component · CPC title

• G02F2201/305

  diffraction grating · CPC title